John Llewelyn James from Derry was jailed in August 2008 for 18 months after admitting downloading more than 20,000 indecent images of children being sexually abused.

He was working for a charity for disabled people with learning disabilities at the time. When his work and home computers and two memory sticks were examined officers uncovered a total of 22,242 images — one of the highest totals ever uncovered in the province. Jailing him, Judge Philip Babbington said James knew what he was doing was wrong but had not stopped downloading the images from the internet “for your own selfish sexual gratification”.

Downpatrick man Ian Magill — who once paid a mother in Thailand just £155 to let him take indecent photographs of her children — was jailed for two years in 2007 after he was caught in possession of more than 15,000 images of child abuse. Investigating officers described the images Magill was in possession of as the most horrific they had ever seen. On top of this Judge Peter Gibson told Magill that the case “was one of the worst he ever had the misfortune to encounter”. A number of DUP politicians protested in Stormont against the “leniency” of the sentence given to Magill.

Last year a retired Belfast schoolteacher who downloaded more than 2,500 pornographic photographs of children as young as six from the internet was given a suspended prison sentence. Thomas Norman McKeown, who taught at Grosvenor Grammar School for 37 years, viewed the child porn on his home computer. He admitted downloading 2,685 images of young girls over a two-year period. Downpatrick Crown Court heard that two photos were of sexual activity between adults and children. The married grandfather pleaded guilty to 26 counts of making an indecent photo of a child over a period from January 2005 to January 2007.

In 2000 Carey Lyons from Doagh Road in Newtownabbey, Co Antrim, was jailed for six months. He admitted making and distributing indecent pictures of children. The court was told that police had found compact discs containing up to 50,000 still and moving indecent images of children hidden under his bed. It was the first case of its kind to come to court in Northern Ireland. He was jailed again in 2005 for a total of 26 charges of downloading nearly 350 “revolting, and in many cases very distressing” images of children being sexually abused after admitting to police he had been “at it again”.

One of Northern Ireland’s most notorious child sex offenders died last year while awaiting trial on charges of making and possessing indecent images of a child. John Linton Corry had previously been convicted of indecently assaulting a young girl between May 1989 and May 1991, when his victim was aged seven and nine. In December 2007 he appeared in court again charged with making an indecent photograph of a child and possessing an indecent photograph of a child. In February last year he faced another charge of being in possession of an indecent photograph, or pseudo photograph, of a child. He died before he could stand trial.